The present disclosure relates to methods and compositions for use in cementing operations and/or remedial operations in previously-cemented areas in a subterranean formation.
Natural resources such as gas, oil, and water residing in a subterranean formation are usually recovered by drilling a wellbore down into the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe, e.g., casing or liners, is run in the wellbore and cemented into place. Such cementing operations are commonly referred to as primary cementing operations.
In primary cementing operations, a hydraulic cement composition is pumped into the annular space between the walls of the wellbore and the exterior of the pipe string disposed therein. The cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened, substantially impermeable cement therein. The cement sheath physically supports and positions the pipe string in the wellbore and bonds the exterior surfaces of the pipe string to the walls of the wellbore whereby the undesirable migration of fluids between zones or formations penetrated by the wellbore is prevented.
Shear and compressional stresses are commonly exerted on the cement as the result of relatively high fluid pressures and/or temperatures inside the pipe string during testing, hydraulic fracturing, perforating, fluid injection and/or fluid production and as the result of outside forces exerted on the cement sheath due to formation shifting, overburdened pressures, subsidence, and/or tectonic creep. Resins (e.g., epoxy resins) can be used in cement compositions to improve the resiliency, i.e., elasticity and ductility, of the cement sheath to withstand these commonly exerted stresses.
Small openings such as holes or cracks in the casing string, the cement sheath, and/or the wellbore are sometimes formed as a result of these stresses through which fluids can undesirably flow into or out of the wellbore. Due to their resiliency, epoxy resins can also be used to seal the small openings and serve as a barricade against leaks of undesirable fluids. Such sealing operations are commonly referred to as remedial operations.
While embodiments of this disclosure have been depicted, such embodiments do not imply a limitation on the disclosure, and no such limitation should be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.